The last time I had a carb back fire and produce a visible flame, I had the distributor clocked wrong in a 69 Lincoln. That isn't the case here as the distributor has not been pulled and ran fine with the log head. I checked the rotor at tdc and it pointed close to cylinder 1 on the cap (I was worried that I might have had the cap in wrong).
The carb was used and I probably should have overhauled it, but it appeared relatively clean. I get a good shot of gas from accelerator pump, but only out of one of the outlets. I know I should overhaul the carb, but was hoping I could get it to function enough to rule out other problems.
Normally, I try to change stuff out in small increments, but I had this Aussie head on my shelf for quite some time and wanted to give it a shot.